1994 sl w/signal light problem - PeachParts Mercedes-Benz Forum

pep · #1 01-15-2005, 11:33 AM

My 1994 sl500 has intermittent and hazard lights problem. When I replaced the front signal light bulbs, somehow the person helping me to see if the signal lights were working fine, decided to press the hazard switch, the signal light switch and turned the light switch different ways at the same time. Since then, whenever I use my signal light switch, both signal lights blink, whenever I turn my headlights on, the signal lights come on without flashing and the yellow backlights come on too. if I use my signal light switch with my headlights on both signal lights blink also. I've replaced the signal light switch for a new one, replaced the bulbs with new MB OE specification signal light bulbs, replaced module N10/ 2 and removed and cleaned connectors on the hazard switch, but nothing has worked. Ican't use my signal lights when I drive during daylight, nor I can use the car during nightime. Need help fast. Oh most important, Happy New Year to everyone. Thank You, PEP

bobterry99 · #2 01-17-2005, 08:04 AM

Had something like you describe happen to me. I had removed and reinstalled one of the turn signal lenses and the problem occurred. Really odd. As I recall, I fiddled with the bulb within the lens and finally everything operated normally.

You might try removing the front turn signal lamps and see if the problem disappears.

pep · #3 01-19-2005, 08:07 PM

Bobterry99 I took your advice and went right to the signal light lenses and played with the socket and the bulb but it didn't work for me. Do you think that I should take it to the shop and maybe the computer has recorded a fault that can only be fix through there?. Thank You for your input and help, PEP

bobterry99 · #4 01-20-2005, 05:23 AM

I wouldn't go to the shop just yet. There are no diagnostics for any of the components involved: it's just a matter of troubleshooting the circuit.

The lamps are being powered by either N10/2 or the instrument cluster, or maybe even possibly the lamp failure module (N7). You mentioned you fiddled with one of the bulbs. But did you try removing both left and right front bulbs together and see what happened, PEP?

Carlos Serrano · #5 01-20-2005, 09:40 AM

Sound like a ground wire problem, it might be that simple, at least the symptons are consistence with any other vehicle with blinker problems, you might want to check the wire connection behind the bulbs.Just a suggestion

pep · #6 01-24-2005, 02:11 PM

I was given by the young man at the mercedes dealer parts dept., the wrong front signal light bulbs. I finally replaced them with the right ones and the system seems to be back to normal except for the the signal light switch that's only signaling to the right regardless to where you signal to. For example, if I signal to the left it will blink the right signal light and if I signal to the right, it will also signal to the right. At the beginning of this ordeal, I replaced the signal light switch with one that I purchase through EBAY, and threw the old away thinking that this was the problem. And also, I replaced the light switch with a brand new. Could any of this two replaced parts could be the problem for the signal light malfunction. By the way, I did not complain to the parts dept. manager as to how much I've due to their mistake, because it was a young person, I guess at a new job, and I didn't want to jeopardize his bread and butter. We all make mistakes! Thank You for your help, PEP.

bobterry99 · #7 01-26-2005, 07:34 AM

I don't quite follow you, PEP. If you signal a left turn, what happens with (1) the front turn signal lamps, (2) the rear turn signal lamps, and (3) the indicator lamps in the instrument cluster?

pep · #8 01-26-2005, 08:06 PM

Bobterry99 If I signal a left turn the front and back signal lights as well as the indicator lamp on the cluster show signaling to the right. If I signal to the right all of the above signals to the right as well. It never shows signaling to the left regardless to where I signal to. Thank You again for your prompt response and help. PEP

bobterry99 · #9 01-27-2005, 03:40 AM

The headlamp switch wouldn't affect your turn signals, pep. Of course, the new turn signal switch you bought could be bad. You can check it in two places. At the connector at the end of the switch: with the connector seperated, pin #10 shorts to pin #4 for a left turn, and pin #9 shorts to pin #4 for a right turn. At the input to the turn signal "Combination relay module": with the module removed, you would measure 12-volts on socket #12 for a left turn and 12-volts on socket #6 for a right turn.

If the switch is fine, you probably have a bad Combination relay module. Location is shown in the picture.

Gilly · #10 01-27-2005, 08:30 AM

One other idea:
I had a situation very similar to this in a 140 chassis S Class, similar year, and these are both wired very similarly.
The case I had, it was the ignition switch, believe it or not. The turn signal sends out left AND right on the same wire, it's voltage coded. The ignition switch wasn't sending enough power through the turn signal fuse, both left and right were both sending out about the same (stepped down) voltage, instead of what the one direction needed to be (full 12 volts). If you can find the fuse in the fusebox listed as "turn signal", and jumped 12 volts to it (as a test), the directionals should work as normal. If this happens, I'd replace the ignition switch.

Gilly